GOES-16 Mid-level Water Vapor (6.9 µm) images with an overlay of GLM Flash Extent Density (above) showed that there were isolated brief periods of lightning activity over parts of West Virginia / Maryland / Pennsylvania during the nighttime hours, followed by more activity off the south coast of Massachusetts during the daytime hours on 13 February 2024. Although this lightning was occurring near areas receiving moderate to heavy snowfall, there were no METAR sites that explicitly reported thundersnow.

As clouds slowly began to clear, GOES-16 Day Cloud Type RGB images (below) began to reveal areas with appreciable snow cover (darker shades of green).

On the following day, with minimal cloud cover RGB imagery showed the areal extent of the swath of fresh snow cover that extended from West Virginia to Massachusetts (below). Notable snowfall accumulations included 15+ inches in Pennsylvania, New Jersey and Connecticut (storm summary).

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A sequence of Suomi-NPP VIIRS Infrared Window (11.45 µm) images (above) displayed the development of a coma-shaped cloud structure associated with a low pressure system near the North Pole (northwest of Greenland) on 13 February 2024. The single METAR surface report plotted is Svalbard, Norway (the reports for CWLT — Alert, Nunavut, Canada — were not available).

Analyses from the Canadian Meteorological Centre (below) showed the evolution of the surface low.

Given the relatively frequent overpasses of polar-orbiting satellites over the high latitudes, cloud-tracked Atmospheric Motion Vectors (AMVs) can be calculated using Infrared data from VIIRS — examples that combine AMVs from Suomi-NPP and NOAA-20 (source) are shown below.

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CSPP software processes signals at Direct Broadcast antenna sites to create products and imagery with very low latency from Low-Earth Orbit (LEO) satellites. The software includes Microwave Integrated Retrieval System (MIRS) algorithms, including rain rate (available here). How well does that product do in capturing observed precipitation? The toggle above shows GOES-16 Clean Window infrared imagery and derived rain rates (derived from microwave data). The back edge of the precipitation is captured well by the MIRS product, and several heavier bands of precipitation offshore are also suggested. This product is especially useful in the absence of any radar.

How does the rain rate compare to the radar at the same time? The image below (from the College of DuPage website) shows Mosaic Reflectivity at 1750 UTC on 13 February. The back edge of the precipitation in the radar shows agreement with the Rain Rate shown in the toggle above (or here).

The side-by-side comparison, below, highlights detected features. The precipitation band circled in purple appears in both Rain Rate and Radar imagery. The heavier precipitation regions to the east, highlighted by the blue arrows, does not appear in the radar, and highlights an advantage of MIRS Rain Rate: it provides information where radar data are not available.

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On February 12, 2024, much of inland Alaska is experiencing warnings for wintery precipitation, while coastal Alaska is under warnings for storms, gales, and heavy freezing spray. Southeastern Alaska is also under a small craft advisory.

The low-pressure system associated with this inclement weather is seen easily from the GOES-West imagery. Viewers can see a large hook-shaped rotational system swooping in from the south and affecting much of the state. Figure 2 shows Band 9, the mid-level water vapor channel, from GOES-West, illustrating the low pressure system nicely. On the GOES-West Advanced Baseline Imager (ABI), Band 9 is centered on 6.9 µm and is great for tracking storm systems.

Expectedly, the weather is having unfavorable effects on aviation safety. Marginal visual flight rules (MVFR) cite weather conditions that aircraft pilots can experience at land or ocean surface levels. As seen in Figure 3, satellite and model-derived MVFR probabilities are present throughout inland and coastal areas of Alaska.

The animations in this post are replicable for anyone with web access, using RealEarth. RealEarth is a free weather visualization application. To recreate the animations you see in this post, click the links in the animation captions.

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